The book "Introduction to Philosophy" offers an in-depth exploration of the fundamental questions of philosophy, based on the lecture by Edmund Husserl from the winter semester of 1922/23. In this lecture, the central problem of ultimate justification is addressed, which is crucial for the development of a philosophical system. Husserl argues that a radical philosophical ultimate justification is only possible through a phenomenological transcendental philosophy that proves itself in apodictic self-criticism. This critical engagement is an indispensable part of his First Philosophy and represents an important addition to his later writings. Thus, this volume is not only an introduction to philosophy but also a significant work for understanding Husserl's philosophical approach.